1. Field of the Invention
The present invention relates to a leg unit, more particularly to a telescopic leg unit for table and chair, in which two telescopically connected tubes are rotatable relative to each other between an unlock position and a locked position.
2. The Prior Arts
The advance of artistic technology, a majority of customers take into account the convenient usage, lasting period and safety measurements of a product in addition to the quality and price of the product Regarding a table or chair, the length of the table leg, is generally fixed such that the height of the table cannot be altered in order to suit the user of variation height. Especially for a study table, which user grows up from a childhood to an adult, his study table becomes useless due to unable to adjust the height of table legs.
To eliminate the problems caused due to lacking height adjustment of table legs, a telescopic leg unit has be proposed, which mainly includes an outer tube and an inner tube telescopically inserted into or retracted from the outer tube, after which manually operated fixing means are used to fix the height or the length of the leg unit. The manually fixing means include the following:    1. Screw threads method: the outer and inner tubes have inner and outer screw threads at the connection parts thereof. However, a table has at least three leg units and it is somewhat difficult and time-consuming to adjust three of the leg units into the same height by means of user hands.    2. Pin insert type: a fixing pin is inserted through the fixing holes in the outer and inner tubes so as to adjust the desired height of the leg unit. The problems are that it is laborious to align and insert the fixing pin into the fixing holes of the inner and outer tubes after removing the two tubes relative to each other. Moreover, the fixing pin when protrudes outwardly and radially from the inner and outer tube may scratch or injures the user accidentally.    3. Ratchet teeth fixing method: after axial adjustment of the telescopically connected outer and inner tubes, one is rotated in a single direction relative to the other so as to fix the two tubes together. In case the adjusted length of the two tubes does not fit the desired length, the inner tube needs be axially pulled out from the outer tube and re-adjust of the length needs be conducted, which results in waste of manual labor.